

public class MySingleList implements IList{
        static class ListNode{
            public int val;
            public ListNode next;

            public ListNode(int val) {
                this.val = val;
            }
        }
        public ListNode head;
        public void create(){
            ListNode node1=new ListNode(12);
            ListNode node2=new ListNode(23);
            ListNode node3=new ListNode(34);
            ListNode node4=new ListNode(45);
            node1.next=node2;
            node2.next=node3;
            node3.next=node4;
            head=node1;
        }
        @Override
        public void display() {
            ListNode cur=head;
            while(cur!=null){
                System.out.print(cur.val+" ");
                cur=cur.next;
            }
            System.out.println();
        }
        @Override
        public void addFirst(int data) {
            ListNode node=new ListNode(data);
            node.next=head;
            head=node;
        }

        @Override
        public void addLast(int data) {
            ListNode  node=new ListNode(data);
            if(head==null){
                head=node;
            }else {
                ListNode cur = head;
                while (cur.next != null) {
                    cur = cur.next;
                }
                cur.next = node;
            }

        }

        @Override
        public void addIndex(int index, int data) {
            if(index < 0 || index > size()) {
                throw new IndexException("index不合法的: "+index);
            }
            ListNode node=new ListNode(data);
            if(head==null){
                head=node;
                return;
            }
            if(index==0){
               node.next=head.next;
               head=node;
               return;
            }
            if(index==size()){
                addLast(data);
                return;
            }
            ListNode cur=head;
            int count=0;
            while(count!=index-1){
                cur=cur.next;
                count++;
            }
            node.next=cur.next;
            cur.next=node;

        }

        @Override
        public boolean contains(int key) {
            ListNode cur=head;
            while(cur!=null){
                if(cur.val==key){
                    return true;
                }
                cur=cur.next;
            }
            return false;
        }

        @Override
        public void remove(int key) {
            if(head==null){
                return;
            }
            if(head.val==key){
                head=head.next;
                return;

            }
           ListNode cur=findPrevKey(key);
            if(cur==null){
                return;
            }
            ListNode del=cur.next;
            cur.next=del.next;
        }
    private ListNode findPrevKey(int key){
            ListNode cur=head;
            while(cur.next!=null){
              if(cur.next.val==key) {
                  return cur;
              }else {
                  cur=cur.next;
              }
            }
            return null;
    }
    @Override
    public void removeAllKey(int key) {
      if(head==null){
          return;
      }
        ListNode pre=head;
        ListNode cur=head.next;
      while(cur!=null){
         if(cur.val==key){
           pre.next=cur.next;
           cur=cur.next;
         } else {
           pre=cur;
           cur=cur.next;
           }

       }
        if(head.val==key){
            head=head.next;

      }
    }

        @Override
        public int size() {
          ListNode cur=head;
          int count=0;
          while(cur!=null){
              count++;
              cur=cur.next;
          }
          return count;
        }

        @Override
        public void clear() {
                head=null;
        }


}
